Conventionally, a rotary cone drill bit comprises a body attached to the drill string with journal legs extending downward from the body. A cone cutter is mounted on the lower end of each journal leg. As the drill string rotates the cone cutter disintegrates the earth formation beneath the drill bit and forms a bore hole.
During normal operations a drilling fluid is pumped down through the drill string and into the area around the rotary cone drill bit. Ideally the drilling fluid creates a cross-flow across the bottom of the bore hole. The drilling fluid washes the cuttings, formation fragments and other debris away from the interface of the drill bit and the formation and then carries this material through the annulus between the drill string and the bore hole up to the surface. This aids the drill bit in cutting new formation rather than recutting debris in the bore hole. However, use of prior devices for injecting drilling fluid into the bore hole has not provided efficient removal of the formation fragments to the annulus of the drill bit. Therefore the drill bit is re-cutting formation fragments during a significant part of the drilling operation. This reduces both the efficiency and the life of the drill bit.